arm64: bpf: fix JIT frame pointer setup

BPF fp should point to the top of the BPF prog stack. The original
implementation made it point to the bottom incorrectly.
Move A64_SP to fp before reserve BPF prog stack space.

CC: Zi Shen Lim <zlim.lnx@gmail.com>
CC: Xi Wang <xi.wang@gmail.com>
Signed-off-by: Yang Shi <yang.shi@linaro.org>
Reviewed-by: Zi Shen Lim <zlim.lnx@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 3 deletions

diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c
index a44e5293c6f5..ac8b548ce493 100644
--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -161,12 +161,12 @@ static void build_prologue(struct jit_ctx *ctx)
         if (ctx->tmp_used)
                 emit(A64_PUSH(tmp1, tmp2, A64_SP), ctx);
 
-        /* Set up BPF stack */
-        emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
-
         /* Set up frame pointer */
         emit(A64_MOV(1, fp, A64_SP), ctx);
 
+        /* Set up BPF stack */
+        emit(A64_SUB_I(1, A64_SP, A64_SP, stack_size), ctx);
+
         /* Clear registers A and X */
         emit_a64_mov_i64(ra, 0, ctx);
         emit_a64_mov_i64(rx, 0, ctx);